Solid state imaging device, method of controlling solid state imaging device, and program for controlling solid state imaging device

ABSTRACT

A solid state imaging device includes: a pixel array unit that has a plurality of pixels 2-dimensionally arranged in a matrix and a plurality of signal lines arranged along a column direction; A/D conversion units that are provided corresponding to the respective signal lines and convert an analog signal output from a pixel through the signal line into a digital signal; and a switching unit that switches or converts the analog signal output through each signal line into a digital signal using any of an A/D conversion unit provided corresponding to the signal line through which the analog signal is transmitted, and an A/D conversion unit provided corresponding to a signal line other than the signal line through which the analog signal is transmitted.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit under 35 U.S.C. § 120 as acontinuation application of U.S. patent application Ser. No. 15/490,590,filed on Apr. 18, 2017, which is a continuation application of U.S.patent application Ser. No. 15/397,631, filed on Jan. 3, 2017, which isa divisional application of U.S. patent application Ser. No. 15/298,574,filed Oct. 20, 2016, now U.S. Pat. No. 9,609,240, which is acontinuation application of U.S. patent application Ser. No. 14/622,681,filed Feb. 13, 2015, now U.S. Pat. No. 9,692,994, which is acontinuation application of U.S. patent application Ser. No. 13/598,986,filed Aug. 30, 2012, now U.S. Pat. No. 9,094,623, which claims priorityfrom Japanese Patent Application No. 2011-207368 filed in the JapanesePatent Office on Sep. 22, 2011, the entire contents of each of which isincorporated herein by reference.

BACKGROUND

The present disclosure relates to a solid state imaging device includinga pixel array unit that has a plurality of 2-dimensionally arrangedpixels in a matrix and a plurality of signal lines arranged along acolumn direction, and an A/D (analog/digital) conversion unit isprovided corresponding to each signal line and converts an analog signaloutput from the pixel through the signal line into a digital signal, amethod of controlling the solid state imaging device, and a program forcontrolling the solid state imaging device.

A pixel adding method in a solid state imaging device is known as an FDadding method of summing and outputting charges of pixels on a floatingdiffusion (hereinafter, referred to as FD) of the pixel, a sourcefollower adding method of simultaneously reading a plurality of pixelsignals through reading lines and adding the pixel signals using a loadMOS circuit connected to the reading signal lines, a counter addingmethod of performing digital addition using a counter circuit in acolumn ADC circuit, and a capacity adding method of connecting aplurality of capacitors to input ends of a comparator in a column ADCcircuit in parallel and adding signals of a plurality of vertical signallines.

The pixel addition in decimation reading of Bayer arrangement will bedescribed with reference to FIG. 29 to FIG. 31B. FIG. 29 is a diagramillustrating an example of pixel addition performed using a column ADCcircuit when the Bayer arrangement is used as a color filter array, FIG.30 is a timing chart at the time of the pixel addition in the column ADCcircuit shown in FIG. 29, and FIG. 31A and FIG. 31B are reading imageswhen the column ADC circuit shown in FIG. 29 is used.

In the Bayer arrangement shown in FIG. 29, G color filters used as maincomponents of brightness signals are disposed at an interval of onepixel in a checkerboard shape, R and B color filters are arranged at theremaining pixels at a pitch of vertical and horizontal one pixel in acheckerboard shape, and the R and B color filters are disposed toobliquely deviate by one pixel. The pixel array shown in FIG. 29 isconfigured by a pixel unit (hereinafter, referred to as an FD sharingpixel unit) that shares the FD by connection of four pixels of verticaland horizontal 2×2 through a floating diffusion (hereinafter, referredto as FD).

In the configuration shown in FIG. 29, addition and addition averagingare performed, for example, as R1 and R2, G1 and G3, G2 and G4, B1 andB2, R3 and R4, G5 and G7, G6 and G8, and B3 and B4, the same verticalsignal line is shared, the same color of pixels are sequentially inputto the column ADC circuit in the vertical direction, are A/D convertedusing the column ADC circuit of each column, and then the addition andthe addition averaging is performed by a counter (for example, seeJapanese Unexamined Patent Application Publication No. 2006-033454).

For example, as shown in FIG. 30, first, the pixel R1 and the pixel R3are selected, the pixel signal of the pixel R1 is output to a verticalsignal line VSL1, and the pixel signal of the pixel R3 is output to avertical signal line VSL2. Then, the pixel R2 and the pixel R4 areselected, the pixel signal of the pixel R2 is output to the verticalsignal line VSL1, and the pixel signal of the pixel R4 is output to thevertical signal line VSL2.

That is, the pixel signals of pixels R1 and R2 are sequentially outputto the vertical signal line VSL1, and the pixel signals of pixels R3 andR4 are sequentially output to the vertical signal line VSL2.Accordingly, both pixel signals of the pixels R1 and R2 are counted by acounter CNT1, and both pixel signals of the pixels R3 and R4 are countedby a counter CNT2.

Similarly, the remaining pixels are sequentially selected and output tothe vertical signal lines, and digital data subjected to counteraddition by the counters are output.

FIG. 31A is a reading image in a state of addition in the column ADCcircuit, and an image output from the column ADC circuit corresponds toa state where the number of pixels in the vertical direction isdecimated by half.

Thereafter, the A/D conversion value of the pixel output from the columnADC circuit is transmitted to a logic signal processing circuit at thelatter stage, and the addition and the addition averaging are performedtherein in the horizontal direction. FIG. 31B is a reading image in astate of addition in the logic signal processing circuit, an imageoutput from the logic signal circuit corresponds to a state where thenumber of pixels in both vertical and horizontal directions is decimatedby half.

Recently, in a solid state imaging device, white as a main component ofa brightness signal may be used in color arrangement of a color filterarray (for example, see Japanese Unexamined Patent ApplicationPublication No. 2010-136226).

FIG. 32 is an example of color arrangement of a color filter arrayincluding white. In the color arrangement shown in FIG. 32, whitefilters are disposed at a pitch of one pixel in a checkerboard shape,and RGB color filters are uniformly disposed at the remaining pixels.More specifically, the R and B color filters are arranged incheckerboard shape at a pitch of two pixels horizontally and vertically,the R and B color filters are disposed to obliquely deviate by onepixel, and the remaining pixels are the G color filters. In this case,the G filters are arranged in an oblique stripe shape.

In such color arrangement, it is difficult to perform the addition andthe addition averaging using the column ADC circuit. Accordingly, theA/D conversion value of the pixel output from the column ADC circuit istransmitted to the logic signal processing circuit at the latter stage,the vertical direction addition and addition averaging and thehorizontal direction addition and addition averaging are performedtherein by a calculation process.

When the process of decimation of the addition and the additionaveraging in the logic signal processing circuit is performed whileusing the color arrangement shown in FIG. 29, all sixteen pixels in the4×4 pixel arrangement are selected, and the AD conversion is performedusing the column ADC circuit provided corresponding to each verticalsignal line to perform the addition and the addition averaging. That is,also at the time of the decimation outputting, it is necessary tooperate all the ADC circuits, and power consumption in the column ADCcircuits is not reduced.

It is necessary to transmit the addition and the addition averagingvalue obtained by the AD conversion to the logic signal processing unitat the latter stage and to perform the addition and the additionaveraging in the horizontal direction. Accordingly, the logic signalprocessing unit at the latter stage has to be provided with a circuitfor processing the received value or a line memory, which causes anincrease of any of a circuit scale, an operation speed, and powerconsumption. Of course, these demerits in the logic signal processingunit are the same even in the case of the color arrangement of thefilter array including the white shown in FIG. 32 described above.

In the FD addition method, and the source follower adding method, thecounter adding method, and the capacity adding method in the related artdescribed above, when the color arrangement shown in FIG. 32 isemployed, it is physically difficult to perform the decimationoutputting using the addition and the addition averaging in the pixelsconnected to the other vertical signal lines. In the case of thecapacity adding method, it is possible to perform the decimationoutputting using the addition and the addition averaging in the pixelsconnected to the adjacent vertical signal lines, but it may not beperformed instead of the output method in which the decimation is notperformed.

SUMMARY

It is desirable to provide a solid state imaging device, a method ofcontrolling the solid state imaging device, and a program forcontrolling the solid state imaging device, capable of performing thedecimation outputting based on addition and addition averaging in pixelsconnected to the other vertical signal line without increasing thecircuit scale, the operation speed, and the power consumption.

According to an embodiment of the present disclosure, there is provideda solid state imaging device including: a pixel array unit that has aplurality of pixels 2-dimensionally arranged in a matrix and a pluralityof signal lines arranged along a column direction; A/D conversion unitsthat are provided corresponding to the respective signal lines andconvert an analog signal output from a pixel through the signal lineinto a digital signal; and a switching unit that switches or convertsthe analog signal output through each signal line into a digital signalusing any of an A/D conversion unit provided corresponding to the signalline through which the analog signal is transmitted, and an A/Dconversion unit provided corresponding to a signal line other than thesignal line through which the analog signal is transmitted.

The solid state imaging device described above includes variousembodiments, for example, the solid state imaging device is embodiedwith the solid state imaging device provided in another apparatus or isembodied by another method. The present technology may be realized as animaging system provided with the solid state imaging device, a controlmethod having processes corresponding to the configurations of thedevice described above, a program for causing a computer to executefunctions corresponding to the configurations of the device describedabove, a computer readable recording medium in which the program isrecorded, and a method of producing the solid state imaging device.

As described above, according to the present technology, it is possibleto provide a solid state imaging device capable of performing thedecimation outputting based on addition and addition averaging in pixelsconnected to the other vertical signal line without increasing a circuitscale, an operation speed, and power consumption.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a configuration of a solid stateimaging device.

FIG. 2 is a diagram illustrating a column processing unit according to afirst embodiment.

FIG. 3 is a table illustrating correspondence of ON/OFF of a switchaccording to the first embodiment.

FIG. 4 is a diagram illustrating an example of a circuit in which theswitch according to the first embodiment is specifically realized.

FIG. 5 is a truth table of a control signal according to the firstembodiment.

FIG. 6 is a diagram illustrating a column processing unit according to asecond embodiment.

FIG. 7 is a table illustrating correspondence of ON/OFF of a switchaccording to the second embodiment.

FIG. 8 is a diagram illustrating an example of a circuit in which theswitch according to the second embodiment is specifically realized.

FIG. 9 is a truth table of a control signal according to the secondembodiment.

FIG. 10 is a circuit diagram illustrating an example of a basic pixelcircuit of a CMOS image sensor.

FIG. 11 is a diagram illustrating an FD sharing pixel unit.

FIG. 12 is a circuit diagram illustrating an example Of a circuitconfiguration of the FD sharing pixel unit.

FIG. 13 is a diagram illustrating configurations of a color filter arrayand a column processing unit according to the first embodiment.

FIG. 14 is a timing chart according to an addition operation of thefirst embodiment.

FIG. 15A and FIG. 15B are diagrams illustrating a reading image in theaddition operation described with reference to FIG. 13 and FIG. 14.

FIG. 16 is a timing chart illustrating the addition operation of thefirst embodiment performed while adjusting the gain.

FIG. 17 is a diagram illustrating a reading image obtained as a resultof the gain adjustment shown in FIG. 16.

FIG. 18 is a diagram illustrating configurations of a color filter arrayand a column processing unit according to the second embodiment.

FIG. 19 is a timing chart according to an addition operation of thesecond embodiment.

FIG. 20A and FIG. 20B are diagrams illustrating a reading image in theaddition operation described with reference to FIG. 18 and FIG. 19.

FIG. 21 is a timing chart illustrating the addition operation of thesecond embodiment performed while adjusting the gain.

FIG. 22 is a diagram illustrating a reading image obtained as a resultof the gain adjustment shown in FIG. 21.

FIG. 23 is a diagram illustrating configurations of a color filter arrayand a column processing unit according to a third embodiment.

FIG. 24 is a timing chart according to an addition operation of thethird embodiment.

FIG. 25A and FIG. 25B are diagrams illustrating a reading image in theaddition operation described with reference to FIG. 23 and FIG. 24.

FIG. 26 is a timing chart illustrating the addition operation of thethird embodiment performed while adjusting the gain.

FIG. 27 is a diagram illustrating a reading image obtained as a resultof the gain adjustment shown in FIG. 26.

FIG. 28 is a diagram illustrating a relationship of connection accordingto a third modification example.

FIG. 29 is a diagram illustrating an example of pixel addition performedusing the column ADC circuit when a Bayer arrangement is used as a colorfilter array.

FIG. 30 is a timing chart at the time of circuit addition in the columnADC circuit shown in FIG. 31A and FIG. 31B.

FIG. 31A and FIG. 31B are reading images when the column ADC circuitshown in FIG. 31A and FIG. 31B is used.

FIG. 32 is an example of color arrangement of a color filter includingwhite.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present technology will be described inthe following order.

(1) Configuration of Solid State Imaging Device:

(2) First Embodiment of Pixel Addition:

(3) Second Embodiment of Pixel Addition:

(4) Third Embodiment of Pixel Addition:

(5) Various Modification Examples:

(1) Configuration of Solid State Imaging Device

FIG. 1 is a block diagram illustrating a configuration of a solid stateimaging device. In the embodiment, a CMOS image sensor that is a kind ofX-Y address type solid state imaging device will be described as anexample of an imaging device.

Hereinafter, it will be described that NMOS is used in all the pixels ofthe CMOS image sensor, but this is an example, a device that is a targetof the present technology is not limited to the MOS type solid stateimaging device. For example, a plurality of unit constituent elementshaving sensitivity with respect to electromagnetic waves input from theoutside such as light and radiation are arranged in line or matrix, andall the embodiments are similarly applied to all the semiconductordevices for detecting physical distribution to read a signal by anaddress control.

The solid state imaging device 100 has a pixel unit in which a pluralityof pixels including light receiving elements outputting a signalcorresponding to incident light quantity are 2-dimensionally disposed ina matrix, a signal output from each pixel is a voltage signal, and ADconversion units (ADC: Analog Digital Converters) are provided in lineparallel.

Herein, the line parallel means that the same number of AD conversionunits as the number of vertical signal lines (an example of columnsignal lines) disposed in parallel with the vertical columns of thepixels constituting the image sensor are disposed one-to-onecorresponding to the vertical signal lines, and one AD conversion unitcorresponds to one line (one vertical signal line).

As a general example in which the ADC circuits are provided in lineparallel, there is a column type in which an analog signal processingunit or an ADC circuit is provided for each vertical signal line at aportion called a column area provided on the output side of an imagingunit, and signals are sequentially read on the output side.

The present disclosure is not limited to the column type (the lineparallel type), and a type of assigning one ADC circuit to a pluralityof (for example, two) adjacent vertical signal lines, or a type ofassigning one ADC circuit to N (N is an integer: N−1 vertical signallines are disposed therebetween) vertical signal lines of N intervalsmay be employed.

Even in any type other than the column type, a plurality of verticalsignal lines share one ADC circuit, and thus a switching circuit (aswitch) that supplies a plurality of pixel signals corresponding to aplurality of columns supplied from the pixel array unit 30 to one ADCcircuit is provided. According to a process at the latter stage, aseparate countermeasure is necessary, for example, a memory for storingan output signal is provided.

Various AD conversion methods are conceivable from the viewpoint ofcircuit scale, processing speed (a high speed), and resolution, forexample, there is a slope integration type or a ramp signal comparisontype (hereinafter, in the specification, a reference signal comparisontype).

In the reference signal comparison type, an analog signal that is atarget of AD conversion is compared with a ramp-shaped reference signal(a ramp wave), a value of which is gradually changed, and a digitalvalue of the analog signal that is the target of the AD conversion isacquired on the basis of a count value obtained by counting acontinuation time of a comparison process. In the embodiment, there is aramp signal comparison type AD conversion method.

When the reference signal comparison type AD conversion method isemployed, it is conceivable to provide a plurality of reference signalgenerating units. For example, a reference signal generating unit thatsupplies reference signal to odd numbered columns in vertical signallines and a reference signal generating unit that supplies referencesignals to even numbered columns may be provided, or the referencesignal generating units may be provided in line parallel (for eachsignal line).

However, when the plurality of reference signal generating units areprovided, a circuit scale or power consumption is increased. In theembodiment, the reference signal generating unit is provided commonlywith all the columns, and the column type ADC circuit providedcorresponding to each vertical signal line commonly uses the referencesignal generated from the reference signal generating unit.

Hereinafter, a specific example of a solid state imaging device will bedescribed with reference to FIG. 1. As shown in FIG. 1, a solid stateimaging device 100 includes a color filter array 10 and a semiconductorsubstrate 20.

The semiconductor substrate 20 is provided with a pixel array unit 30, avertical driving unit 40, a horizontal driving unit 50, a timing controlunit 60, a column processing unit 70, a reference signal generating unit80, and an output circuit 90. A digital operation unit may be providedat the front end of the output circuit 90 as necessary. The digitaloperation unit is provided, for example, when a process of decimationpixel signals in the horizontal direction or vertical direction isperformed by addition and addition averaging.

The pixel array unit 30 is provided with a color filter array 10 inwhich colors of filters are classified corresponding to pixels on thelight reception face side, and pixels PXL including a photodiode as aphotoelectric conversion element are arranged in a matrix. A specificcircuit configuration of the pixel PXL and color arrangement of thecolor filter array 10 will be described later in detail.

The pixel array unit 30 is provided with n pixel driving lines HSLn (nis an integer equal to or more than two) and m vertical signal linesVSLm (m is an integer equal to or more than two). The pixel drivinglines HSLn are disposed at the same distance along the left and rightdirection of the figure (a pixel arrangement direction of pixel rows,and a horizontal direction), the vertical signal lines VSLm are disposedat the same distance along the up and down direction of the figure (apixel arrangement direction of pixel columns, and a vertical direction).

One end of the pixel driving line HSLn is connected to an outputterminal corresponding to each row of the vertical driving unit 40. Oneend of the vertical signal line VSLm is connected to an ADC circuitcorresponding to each vertical signal line VSLm in the column processingunit 70. In addition, specific disposition of the pixel driving linesHSLn and the vertical signal lines VSLm will be described with thedescription of a unit pixel to be described later.

The driving control unit including the vertical driving unit 40, thehorizontal driving unit 50, the timing control unit 60, and the like isprovided on the outside of the pixel array unit 30, and performs acontrol of sequentially reading signals from the pixels constituting thepixel array unit 30.

The timing control unit 60 includes a timing generator and acommunication interface. The timing generator generates various clocksignals on the basis of a clock (a master clock) input from the outside.The communication interface receives data of instructing an operationmode given from the outside of the semiconductor substrate 20, andoutputs data including internal information of the solid state imagingdevice 100.

The timing control unit 60 generates a clock with the same frequency asthat of the master clock, a clock formed by dividing it by two, and alow speed clock formed by further dividing it, and supplies the clocksto, for example, the vertical driving unit 40, the horizontal drivingunit 50, and the column processing unit 70.

The vertical driving unit 40 is formed of a shift register or an addressdecoder, and is provided with a vertical address setting unit forcontrolling a row address or a row scanning control unit for controllingrow scanning.

The vertical driving unit 40 can perform reading scanning and flushingscanning.

The reading scanning is scanning of sequentially selecting the unitpixels reading signals. This scanning is sequentially performedbasically in units of rows. However, when the outputs of the pluralityof pixels in a predetermined positional relationship are subjected toaddition or addition averaging to perform decimation of the pixels, thescanning is performed in a predetermined sequence to be described later.

The flushing scanning is preceded from the reading scanning by a time ofa shutter speed in the row in which the reading is performed in thereading scanning or the pixel combination, and is to reset the unitpixels belonging to the row in which the reading is performed or thepixel combination.

The horizontal driving unit 50 sequentially selects the ADC circuits ofthe column processing unit 70 by synchronizing with the clock outputfrom the timing control unit 60, and leads the signal to the horizontalsignal line (the horizontal output line) Ltrf.

The horizontal driving unit 50 is provided with a horizontal addresssetting unit that regulates (selects individual ADC circuits in thecolumn processing unit 70) a reading column in the horizontal direction,and a horizontal scanning unit that leads the signals of the columnprocessing unit 70 to the horizontal signal lines Ltrf according to thereading address regulated in the horizontal address setting unit.

The pixel signals which are signal-processed using the ADC circuitsconstituting the column processing unit 70 by the selective scanning ofthe horizontal scanning unit are sequentially output to the outputcircuit 90 through the horizontal signal lines Ltrf.

The reference signal generating unit 80 is provided with a DAC (DigitalAnalog Converter), synchronizes with the count clock supplied from thetiming control unit 60 from the initial value supplied from the timingcontrol unit 60, generates a saw-tooth wave (a ramp waveform) which istime-variable stepwise, and supplies the signal as the reference signalto the individual ADC circuits of the column processing unit 70.Hereinafter, the reference signal generating unit 80 may be referred toas the DAC 80.

The reference signal generating unit 80 adjusts a cycle of the countclock. Accordingly, when a clock in which the slope of the referencesignal can be adjusted, for example, a clock divided by 1/m with respectto the reference clock is used, it is possible to make the slope to 1/m.In this case, when the count clock supplied to the counter to bedescribed later included in the ADC circuit is as reference, the countvalue is m times. That is, by adjusting the cycle of the count clock, itis possible to adjust the count value in the counter to be describedlater.

For example, when the analog values of two pixels are sequentiallycounted in the ADC circuit as will be described later, it can berealized by doubling the range of AD conversion in order to performaddition averaging of two pixels on the generated count values. When thereference signal of the reference signal generating unit 80 is used, forexample, it is possible to double the range of AD conversion by makingthe slope of the reference signal double the normal clock.

The column processing unit 70 is provided with an ADC circuit 71 m (m isan integer equal to or more than two) provided for each vertical signalline VSLm, converts the analog signal output from the vertical signalline VSLm into a digital signal, and outputs the digital signal to thehorizontal signal line Ltrf according to the control of the horizontaldriving unit 50. Hereinafter, when description is performed withoutattaching reference numerals corresponding to m to the ADC circuit 71 mor the internal configurations (a comparator 72 m, a counter 73 m and amemory 74 m), the description is common in the ADC circuits.

In the embodiment, as shown in FIG. 2 and FIG. 6, the ADC circuit 71includes a comparator 72, a counter 73, and a memory 74. The ADC circuit71 is an example of the A/D conversion unit.

The comparator 72 receives the reference signal generated by thereference signal generating unit 80 and the analog pixel signal outputfrom the pixel through the vertical signal line, and compares thereference signal with the pixel signal. The comparator 72 outputs a highlevel signal or a low level signal according to a magnitude relationshipbetween the reference signal and the pixel signal. When the magnituderelationship between the reference signal and the pixel signal ischanged, the output is inverted between the high level and the lowlevel.

The clock is supplied from the timing control unit 60 to the counter 73,and the counter 73 counts the time from start to end of AD conversion (acount operation valid period). The timing of start and end of ADconversion may be specified on the basis of the start timing of changeof the reference signal or the output inversion of the comparator 72.The reason is because the output inversion of the comparator 72corresponds to the comparison start or the comparison end of thereference signal and the pixel signal.

The count value generated by the counter 73 is a digital value, and isdigital data corresponding to the analog pixel signal input from thepixel to the column processing unit 70 through the vertical signal lineVSLm. The generated data of the counter 73 is stored (latched) in thememory 74.

When count value is generated using a reset component, for example, thecounter 73 performs a down count operation according to the control ofthe timing control unit 60 while the analog signal corresponding to thereset component is output from the vertical signal line VSLm, andperforms an up count operation reverse to the case of the resetcomponent while the analog signal corresponding to the signal componentis output from the vertical signal line. The count value generated asdescribed above is a digital value corresponding to a difference betweenthe signal component and the reset component, and is a signal componentcorrected by the reset component.

The output circuit 90 performs a process of converting the signal outputfrom the pixel array unit 30 to the column processing unit 70 andcorresponding to the color arrangement of the color filter array 10 intothe color arrangement by the calculation process.

FIG. 2 is a diagram illustrating the column processing unit 70 accordingto a first embodiment. In FIG. 2, for simplification of description, twovertical signal lines are shown, and also two ADC circuits included inthe column processing unit 70 are shown.

In FIG. 2, the column processing unit 70 includes ADC circuits 711 and712, and a switch circuit SWa. The ADC circuit 71 is provided with acomparator 72, a counter 73, and a memory 74. The comparator 72 and thecounter 73 provided in the ADC circuit 71 are connected through theswitch circuit SWa. The functions of the comparator, the counter, andthe memory are as described above.

The switch circuit SWa is provided with a switch SWa11, SWa12, SWa21,and SWa22. The comparator 721 and the counter 731 are connected throughthe switch SWa11, and the comparator 722 and the counter 732 areconnected through the switch SWa22. The comparator 721 and the counter732 are connected through the switch SWa12, and the comparator 722 andthe counter 731 are connected through the switch SWa21.

That is, the switch circuit SWa includes a switch connecting thecomparator and counter provided corresponding to the same verticalsignal line, and a switch connecting a comparator provided correspondingto one of a set of two adjacent vertical signal lines and a counterprovided corresponding to the other.

By connection through two kinds of switches, it is possible to performselective counting using any one of the counter provided correspondingto one vertical signal line and the counter provided corresponding tothe other vertical signal line in the set of adjacent vertical signallines.

Specifically, when the switch SWa11 is turned on, it is possible todigital-convert and store the analog signal of the pixel connected tothe vertical signal line VSL1 by the counter 731, and when the switchSWa12 is turned on, it is possible to digital-convert and store theanalog signal of the pixel connected to the vertical signal line VSL1 bythe counter 732.

When the switch SWa22 is turned on, it is possible to digital-convertand store the analog signal of the pixel connected to the verticalsignal line VSL2 by the counter 732, and when the switch SWa21 is turnedon, it is possible to digital-convert and store the analog signal of thepixel connected to the vertical signal line VSL2 by the counter 731.

By summing up the count while the switch SWa11 is turned on and thecount while the switch SWa21 is turned on by addition, it is possible tocause the counter 731 to generate the digital data formed by summing upthe pixel value of the pixel corrected to the vertical signal line VSL1and the pixel value of the pixel connected to the vertical signal lineVSL2.

Similarly, by summing up the count while the switch SWa22 is turned onand the count while the switch SWa12 is turned on by addition, it ispossible to cause the counter 732 to generate the digital data formed bysumming up the pixel value of the pixel corrected to the vertical signalline VSL1 and the pixel value of the pixel connected to the verticalsignal line VSL2.

The counter addition may be realized, after the counting of one pixelsignal is completed, by continuing the counting, using the count valueaccording to the one pixel signal as an initial value of the counting ofthe other pixel signal.

The ON/OFF control of the switches SWa11, SWa12, SWa21, and SWa22 isperformed according to the control performed through the SW control lineby the timing control unit 60 (the switching control unit). FIG. 3 is atable illustrating ON/OFF correspondence of the switches SWa11, SWa12,SWa21, and SWa22.

As shown in FIG. 3, the switch SWa11 and the switch SWa12 areselectively turned on, and the switch SWa22 and the switch SWa21 areselectively turned on. Meanwhile, the ON/OFF of the switch SWa11 and theON/OFF of the switch SWa22 are interlinked, and also the ON/OFF of theswitch SWa12 and the ON/OFF of the switch SWa21 are interlinked.

Hereinafter, the column processing unit 70 connected such that theoutputs are switchable between the ADC circuits corresponding to a setof adjacent vertical signal lines as described above may be referred toas “cross-connection type column processing unit”.

As described above, by appropriately selecting the counter taking incharge of AD conversion by the switch, it is possible to generatedigital data formed by summing up the pixel values of the pixelsconnected to the set of adjacent vertical signal lines by one counter.

The switch circuit SWa is formed as a part of the column processing unit60, and is disposed at the column portion (the outside of the pixelarray). That is, the disposition of the switch circuit SWa is notparticularly limited, and there is a merit of corresponding to variouscombinations according to pixel arrangement. The input destination ofthe digital value as the comparator output which can be taken as onlyone of High and Low is switched, and thus it is easy to case noise atthe time of switching.

FIG. 4 is a diagram illustrating an example in which the switches SWa11,SWa12, SWa21, and SWa22 are specifically realized. The switch shown inFIG. 4 has a configuration of complementary switches in which an NMOStransistor and a PMOS transistor are combined.

The complementary switches are controlled by control signals transmittedthrough two control lines La1 and La2. Hereinafter, the control signaltransmitted through the control line La1 is referred to as CROSS, andthe control signal transmitted through the control line La2 is referredto as XCROSS.

The complementary switches are analog switches including twocomplementary MOS field effect transistors, and are analog switches inwhich a source-drain circuit is disposed in parallel between the inputterminal and the output terminal of the switch, the control signal forcontrolling the switch can be directly applied to a gate of one channelMOS field effect transistor, and can be applied to a gate of the otherchannel MOS field effect transistor through an inverter.

The control signals CROSS and XCROSS are signals in which positivity andnegativity are logic-inverted to each other, and the output of thecomparator provided corresponding to one vertical signal can be input tothe counter provided corresponding to the same one vertical signal lineor can be input to the counter provided corresponding to the othervertical signal, according to the signal state.

FIG. 5 is a truth table of the control signals XCROSS and CROSS.

As shown in FIG. 5, when the control signal XCROSS transmitted throughthe control line La1 is positive logic (High) and the control signalCROSS transmitted through the control signal La2 is negative logic(Low), the switches SWa11 and SWa22 are turned on, and the switchesSWa12 and SWa21 are turned off.

In this case, the output of the comparator provided corresponding to onevertical signal line is input to the counter provided corresponding tothe same one vertical signal line. That is, the analog pixel signaloutput from one vertical signal line is converted into digital data as acount value in the counter provided corresponding to the same onevertical signal line.

Meanwhile, when the control signal XCROSS transmitted through thecontrol line La1 is negative logic and the control signal CROSStransmitted through the control line La2 is positive logic, the switchesSWa11 and SWa22 are turned off, and the switches SWa12 and SWa21 areturned on.

In this case, the output of the comparator provided corresponding to onevertical signal line is input to the counter provided corresponding tothe other vertical signal line. That is, the analog pixel signal outputfrom one vertical signal line is converted into digital data as a countvalue in the counter provided corresponding to the other vertical signalline.

According to the complementary switches described above, it is possibleto realize the switch circuit with the simple configuration bycombination of the PMOS field effect transistor and the NMOS fieldeffect transistor. In a process of producing CMOSLSI, it is possible tomount the switch circuit.

FIG. 6 is a diagram illustrating a column processing unit 70 accordingto a second embodiment. In FIG. 6, for simplification of description,two vertical signal lines are shown, and also two ADC circuits includedin the column processing unit 70 are shown.

In FIG. 6, the column processing unit 70 includes ADC circuits 711 and712, and a switch circuit SWb. The ADC circuit 71 is provided with acomparator 72, a counter 73, and a memory 74. The comparator 72 and thecounter 73 provided in the ADC circuit 71 are connected through theswitch circuit SWb. The functions of the comparator, the counter, andthe memory are as described above.

The switch circuit SWb is provided with a switch SWb11, SWb12, SW22, andSWb23. The comparator 721 and the counter 731 are connected through theswitch SWb11, and the comparator 722 and the counter 732 are connectedthrough the switch SWb22. The comparator 721 and the counter 732 areconnected through the switch SWb12, and the comparator 722 and thecounter 733 provided in an ADC circuit 713 (not shown) are connectedthrough the switch SWb23.

That is, the switch circuit SWb includes a switch connecting thecomparator and counter provided corresponding to one vertical signalline, and a switch connecting a comparator provided corresponding to onevertical signal line and a counter provided corresponding to a verticalsignal line adjacent to one side of one vertical signal line. The oneside described herein is, for example, the right side in FIG. 6, and isthe same side in all the vertical signal lines provided in one solidstate imaging device.

For this reason, it is possible to select any one of the counterprovided corresponding to the vertical signal line and the counterprovided corresponding to the vertical signal line provided to beadjacent to one side of the vertical signal line, and to perform thecounting.

Herein, when the switch SWb11 is turned on, it is possible todigital-convert and store the analog signal of the pixel connected tothe vertical signal line VSL1 by the counter 731, and when the switchSWb12 is turned on, it is possible to digital-convert and store theanalog signal of the pixel connected to the vertical signal line VSL1 bythe counter 732.

When the switch SWb22 is turned on, it is possible to digital-convertand store the analog signal of the pixel connected to the verticalsignal line VSL2 by the counter 732, and when the switch SWb23 is turnedon, it is possible to digital-convert and store the analog signal of thepixel connected to the vertical signal line VSL3 (not shown) by thecounter 733 (not shown).

When the count while the switch SWb12 is turned on and the count whilethe switch SWb22 is turned on by addition are summed up by addition, itis possible to cause the counter 732 to generate digital data formed bysumming up the pixel value of the pixel connected to the vertical signalline VSL1 and the pixel value of the pixel connected to the verticalsignal line VSL2 provided to be adjacent to the right side of thevertical signal line VSL1.

Similarly, when the count while the switch SWb23 is turned on and thecount while the switch SWb33 is turned on by addition are summed up byaddition, it is possible to cause the counter 733 to generate digitaldata formed by summing up the pixel value of the pixel connected to thevertical signal line VSL2 and the pixel value of the pixel connected tothe vertical signal line VSL3 (not shown). The vertical signal line VSL3(not shown) is a vertical signal line provided to be adjacent to theright side of the vertical signal line VSL2, and the counter 733 (notshown) is a counter provided corresponding to the vertical signal lineVSL3.

The ON/OFF of the switch is controlled according to the control of thetiming control unit 60 (the switching control unit) performed throughthe SW control line.

FIG. 7 is a table illustrating ON/OFF correspondence of the switchesSWb11, SWb12, SWb22, and SWb23. The ON/OFF correspondence of theswitches SWb11, SWb12, SWb22, and SWb23 is periodically applied to theswitches provided on the more right side than the switches SWb11, SWb12,SWb22, and SWb23. For example, the switch SWb33 (not shown) describedabove has the same ON/OFF correspondence as that of the switch SWb11.

As shown in FIG. 7, the switch SWb11 and the switch SWb12 areselectively turned on, and the switch SWb22 and the switch SWb23 arealso selectively turned on. Meanwhile, the ON/OFF of the switch SWb11and the ON/OFF of the SWb22 are interlinked, and also the ON/OFF of theswitch SWb12 and the ON/OFF of the switch SWb23 are interlinked.

Hereinafter, the column processing unit connected such that the outputof each vertical signal line can be shifted and output to the verticalsignal line adjacent to one side thereof may be referred to as“shift-connection type column processing unit”.

As described above, the AD conversion of the pixel signal of the pixelconnected to each vertical signal line is selectively performed by onecounter between the counter provided corresponding to the verticalsignal line, and the counter provided corresponding to the verticalsignal line provided by shifting from the vertical signal line to oneside, and thus it is possible to generate the digital data formed bysumming up the pixel values of the pixels connected to two adjacentvertical signal lines.

The switch circuit SWb is formed a part of the column processing unit 60similarly to the case of the cross-connection type column processingunit described above, and is disposed at the column portion (the outsideof the pixel array). That is, the disposition of the switch circuit SWbis not particularly limited, and there is a merit of corresponding tovarious combinations according to pixel arrangement. The inputdestination of the digital value as the comparator output which can betaken as only one of High and Low is switched, and thus it is easy tocase noise at the time of switching.

FIG. 8 is a diagram illustrating an example in which the switches SWb11,SWb12, SWb22, and SWb23 are specifically realized. Similarly to the caseof FIG. 4 described above, the switch shown in FIG. 8 has aconfiguration of complementary switches in which an NMOS transistor anda PMOS transistor are combined.

FIG. 9 is a truth table of the control signals XCROSS and CROSS.

As shown in FIG. 9, when the control signal XCROSS transmitted throughthe control line Lb1 is positive logic (High) and the control signalCROSS transmitted through the control signal La2 is negative logic(Low), the switches SWb11 and SWb22 are turned on, and the switchesSWb12 and SWb23 are turned off. Accordingly, the output of thecomparator provided corresponding to each vertical signal line is inputto the counter provided corresponding to the same vertical signal line.That is, the analog pixel signal output from each vertical signal lineis converted into digital data as a count value in the counter providedcorresponding to the same one vertical signal line.

Meanwhile, when the control signal XCROSS transmitted through thecontrol line Lb1 is negative logic (Low) and the control signal CROSStransmitted through the control line Lb2 is positive logic (High), theswitches SWb11 and SWb22 are turned off, and the switches SWb12 andSWb23 are turned on. Accordingly, the output of the comparator providedcorresponding to each vertical signal line is input to the counterprovided corresponding to the vertical signal line provided to beadjacent to the right side. That is, the pixel signal output from eachvertical signal line is converted into digital data as a count value inthe counter provided corresponding to the vertical signal line providedto be adjacent to the right side.

According to the complementary switches described above, similarly tothe case of the column processing unit on the cross-connection side, itis possible to realize the switch circuit with the simple configurationby combination of the PMOS field effect transistor and the NMOS fieldeffect transistor. In a process of producing CMOSLSI, it is possible tomount the switch circuit.

Next, a specific circuit configuration of the unit pixel will bedescribed. The pixel PXL of the embodiment has a configuration in whichthe plurality of pixels (for example, four pixels) share the floatingdiffusion FD. However, hereinafter, a basic pixel configuration will befirst described, and then the configuration in which four pixels sharethe floating diffusion FD will be described.

FIG. 10 is a circuit diagram illustrating an example of a basic pixelcircuit of a CMOS image sensor formed of four transistors. The pixelcircuit shown in FIG. 10 includes a photodiode PXL1 as a light receivingelement, a transmission transistor PXL2 as a transmission element, atransmission transistor PXL3 as a reset element, an amplificationtransistor PXL4, and a selection transistor PXL5.

The photodiode PXL1 photoelectrically converts incident light into anamount of charges (herein, electrons) corresponding to light quantitythereof.

The transmission transistor PXL2 is connected between a cathode of thephotodiode PXL1 and the floating diffusion FD as the output node. Thetransmission transistor PXL2 is turned on when a transmission signal isinput to a gate thereof (a transmission gate) through a transmissioncontrol line Ltrg. When the transmission transistor PXL2 is turned on,signal charges (herein, optical electrons) accumulated by photoelectricconversion of the photodiode PXL1 are transmitted to the floatingdiffusion FD.

A drain of the reset transistor PXL3 is connected to a power supply lineLVDD, and a source thereof is connected to the floating diffusion FD. Inthe reset transistor PXL3, a reset signal is input from the verticaldriving unit 40 to a gate thereof through a reset control line Lrst. Thereset transistor PXL3 is turned on when a reset pulse is given theretobefore the charge transmission from the photodiode PXL1, and resetspotential of the floating diffusion FD to potential of the power supplyline LVDD by abandoning the charges of the floating diffusion FD to thepower supply line LVDD.

A gate of the amplification transistor PXL4 is connected to the floatingdiffusion FD. The amplification transistor PXL4 is connected to thevertical signal line VSL through the selection transistor PXL5.

The selection transistor PXL5 is turned on when a control signal (anaddress signal or a selection signal) is input to a gate thereof throughthe selection control line Lse1.

When the selection transistor PXL5 is turned on, the amplificationtransistor PXL4 amplifies the potential of the floating diffusion FD,and outputs voltage corresponding to the potential to the verticalsignal line VSL. The voltage output from each pixel through the verticalsignal line VSL is output to the column processing unit 70.

Next, the pixel circuit in which the plurality of pixels share thefloating diffusion FD will be described. Hereinafter, the plurality ofpixels sharing the floating diffusion FD are referred to as “FD sharingpixel unit”.

FIG. 11 is a diagram illustrating the FD sharing pixel unit. In FIG. 11,the pixel array is configured by 16 pixels of 4×4, and is configured bycombination of the FD sharing pixel units U1 and U4 configured by fourpixels of 2×2. Each FD sharing pixel unit shares the FD at the centerthereof, the vertical signal line VSL1 is connected to the FDs of the FDsharing units U1 and U3, and the vertical signal line VSL2 is connectedto the FDs of the FD sharing pixel units U2 and U4.

In the FD sharing pixel units, pixels having the common positionalrelationship based on the FD for the FD sharing pixel units in aplurality of pixels belonging to the same line are driven by the samepixel driving line, and pixels which do not have the common positionalrelationship based on the FD for the FD sharing pixel units are drivenby the other pixel driving line.

Specifically, in FIG. 11, each of the pixels P11 to P14, the pixels P21to P24, the pixels P31 to P34, and the pixels P41 to P44 belong to thesame line. For example, in the line of the pixels P11 to P14, the pixelP11 and the pixel P13 are driven by the same pixel driving line, and thepixel P12 and the pixel P14 are driven by the same pixel driving line.

Of course, the combination of the pixels and the pixel driving linesdescribed above is an example, and may be variously modified. Forexample, by simultaneously driving two or more pixels sharing the FD, avalue formed by adding analog values of two pixels is generated in theFD, and the FD-added analog value may be output to the vertical signalline.

Next, a specific circuit configuration of the FD sharing pixel unit willbe described.

FIG. 12 is a circuit diagram illustrating an example of a circuitconfiguration of the FD sharing pixel unit.

In FIG. 12, the FD sharing pixel unit U is configured by the pixels P11,P12, P21, and P22.

Each unit pixels of the FD sharing pixel unit U includes one ofphotodiodes PD11, PD12, PD21, and PD22, and one of transmissiontransistors Ttrs11, Ttrs12, Ttrs21, and Ttrs 22.

In the line in which the pixels P11 and P12 are disposed, thetransmission control lines Ltrg1 and Ltrg2 are disposed, and in the linein which the pixels P21 and P22 are disposed, the transmission controllines Ltrg3 and Ltrg 4 are disposed.

The transmission control line Ltrg1 is connected to a gate of thetransmission transistor Ttrs11 of the first pixel P11, and thetransmission control line Ltrg2 is connected to a gate of thetransmission transistor Ttrs12 of the first pixel P12. The transmissioncontrol line Ltrg3 is connected to a gate of the transmission transistorTtrs21 of the second pixel P21, and the transmission control line Ltrg4is connected to a gate of the transmission transistor Ttrs22 of thesecond pixel P22.

It is possible to individually drive the transmission control linesLtrg1, Ltrg2, Ltrg3, and Ltrg4 by the vertical driving unit 40, and itis possible to individually control the charge output of each unit pixelfrom the photodiode by the floating diffusion FD.

Meanwhile, the FD sharing pixel unit U is provided with one floatingdiffusion FD, one reset transistor Tres, one amplification transistorTamp, and one selection transistor Tse1, in four pixels P11, P12, P21,and P22.

The reset control line Lrst is connected to a gate of the resettransistor Tres, and the selection control line Lse1 is connected to agate of the selection transistor Tse1.

That is, the resetting of the floating diffusion FD, the amplifying ofthe voltage accumulated in the floating diffusion, and the outputting ofthe signal with respect to the vertical signal line VSL are performedcommonly with the FD sharing pixel unit U.

The FD sharing pixel circuit described above is an example, and thenumber of unit pixels and the line of unit pixels may be appropriatelychanged. For example, the number of unit pixels sharing the FD may benine pixels of 3×3, and may be 64 pixels of 8×8. The unit pixels sharingthe FD may has a configuration of sharing the FD with respect to fourpixels of 1×4, that is, four pixels longitudinally arranged in a line,and may have a configuration of sharing the FD with respect to fourpixels of 4×1, that is, four pixels transversely arranged in a line.

(2) First Embodiment of Pixel Addition

Next, a first embodiment of pixel addition will be described. In thefirst embodiment, a color filter array including white is employed, andthe cross-correction type is employed in the column processing unit.

FIG. 13 is a diagram illustrating configurations of a color filter arrayand a column processing unit according to the first embodiment. Thecolor filter array shown in FIG. 13 shows 16 pixels of 4×4 for briefdescription.

In the color filter array shown in FIG. 13, W (white) filters with thehighest output level are disposed in a checkerboard shape, R (red) and B(blue) filters are arranged in a checkerboard shape at a pitch of twopixels vertically and horizontally, the R and B filters are arranged toobliquely deviate at pitch of one pixel, and the remaining pixels are G(green) filters. In this case, the G filters are arranged in an obliquestripe shape.

Specifically, the W filters are disposed at the checkerboard shape, theR filters are disposed at the fourth of the second line and at thesecond of the fourth line, and the B filters are disposed at the thirdof the first line and at the first of the third line. The arrangement ofthe R filters and the B filters is the checkerboard arrangement at thepitch of two pixels.

The G filters are disposed at the other pixel positions. Of course, thecolor arrangement of the color filter array including the white is notlimited thereto, and various kinds of color arrangement may be employed.

In the pixel array, four pixels of the vertical and horizontal 2×2constitute the FD sharing pixel unit.

Specifically, the upper left four pixels (G1, G2, W1, and W2) constituteone FD sharing pixel unit, and the lower left four pixels (B2, R2, W5,and W6) constitute one FD sharing pixel unit. The FD sharing pixel unitsare connected to the vertical signal line VSL1 through each sharing FD.

The upper right four pixels (B1, R1, W3, and W4) constitute one FDsharing pixel unit, and the lower right four pixels (G3, G4, W7, and W8)constitute one FD sharing pixel unit. The FD sharing pixel units areconnected to the vertical signal line VSL2 through each sharing FD.

The pixel signal output through the vertical signal line VSL1 is inputto the comparator 721. The comparator 721 determines magnitude betweenthe reference signal input from the DAC 80 and the pixel signal. Forexample, when a gradually increased ramp wave is used as the referencesignal, the comparator 721 outputs Low when the reference signal islower than the pixel signal, and outputs High when the reference signalis equal to or higher than the pixel signal.

Meanwhile, the pixel signal output through the vertical signal line VSL2is input to the comparator 722. The comparator 722 determines magnitudebetween the reference signal input from the DAC 80 and the pixel signal.For example, when a gradually increased ramp wave is used as thereference signal, the comparator 722 outputs Low when the referencesignal is lower than the pixel signal, and outputs High when thereference signal is equal to or higher than the pixel signal.

The output terminal of the comparator 721 is connected to the counter731 provided corresponding to the vertical signal line VSL1 through theswitch SWa11, and is connected to the counter 732 provided correspondingto the vertical signal line VSL2 through the switch SWa12. The verticalsignal line VSL2 is a vertical signal line disposed adjacent to thevertical signal line VSL1.

The output terminal of the comparator 722 is connected to the counter732 provided corresponding to the vertical signal line VSL2 through theswitch SWa22, and is connected to the counter 731 provided correspondingto the vertical signal line VSL1 through the switch SWa21. The verticalsignal line VSL1 is a vertical signal line disposed adjacent to thevertical signal line VSL2.

The ON/OFF of The switches SWa11, SWa12, SWa22, and SWa21 is controlledby the SW control signal output through the SW control line by thetiming control unit 60. The switches are turned on or off to satisfy therelationship shown in FIG. 3 described above.

FIG. 14 is a timing chart according to an addition operation of thefirst embodiment.

First, an addition operation of white pixels that are the main componentof brightness will be described. To perform the addition of the whitepixels, the switches SWa11 and SWa22 are turned on, and the switchesSWa12 and SWa21 are turned off.

The pixel W1 and the pixel W3 are selected, the pixel signal of thepixel W1 is output to the vertical signal line VSL1, and the pixelsignal of the pixel W3 is output to the vertical signal line VSL2. Then,the pixel W2 and the pixel W4 are selected, the pixel signal of thepixel W2 is output to the vertical signal line VSL1, and the pixelsignal of the pixel W4 is output to the vertical signal line VSL2.

That is, the pixel signals of the pixels W1 and W2 are sequentiallyoutput to the vertical signal line VSL1, and the pixel signals of thepixels W3 and W4 are sequentially output to the vertical signal lineVSL2.

Since the switches SWa11 and SWa22 are turned on and the switches SWa12and SWa21 are turned off, both pixel signals of the pixels W1 and W2 arecounted by the counter 731, and both pixel signals of the pixels W3 andW4 are counted by the counter 732.

The counter 731 continues the counting by the control of the timingcontrol unit 60 without initializing the count until the counting ofboth pixel signals of the pixels W1 and W2 is completed. Accordingly,the count value of the counter 731 is digital data corresponding to thesumming of the pixel signals of the pixels W1 and W2.

Similarly, the counter 732 continues the counting by the control of thetiming control unit 60 without initializing the count until the countingof both pixel signals of the pixels W3 and W4 is completed. Accordingly,the count value of the counter 732 is digital data corresponding to thesumming of the pixel signals of the pixels W3 and W4.

In other words, the timing control unit 60 does not initialize the countvalues by the counters 731 and 732 until the counting of two pixels asthe addition target, and initializes the count values of the counters731 and 732 when the counting of two pixels as the addition target iscompleted and the count values are output to the memories 741 and 742(see FIG. 2).

When the counting of the pixel signals of two pixels is completed, thecounters 731 and 732 outputs the count values to the memories 741 and742 by the control of the timing control unit 60.

As a result, the digital data formed by summing up the pixels W1 and W2and the digital data formed by summing up the pixels W3 and W4 arestored in the memories 741 and 742, respectively. The digital datastored in the memories 741 and 742 are output to the output circuit 90through the horizontal signal lines, during the addition processperformed thereafter by the control of the timing control unit 60.

By performing the same addition operation on the pixels W5, W6, W7, andW8 that are the other white pixels, the digital data formed by summingup the pixels W5 and W6 and the digital data formed by summing up thepixels W7 and W8 are stored in the memories 741 and 742, and the digitaldata are output to the output circuit 90 through the horizontal signallines during the addition process performed thereafter by the control ofthe timing control unit 60.

Next, the addition operation of the R, G, and B pixels will bedescribed. In the embodiment, the addition operation of the white pixelsis first performed, and the addition operation of the RGB pixels isperformed thereafter. However, of course, the sequence may be reverseand alternate, and the sequence may be appropriately changed.

To add the R, G, and B pixels, first, the switches SWa11 and the SWa22are turned off, and the switches Swa12 and SWa21 are turned on. Thepixel G1 and the pixel B1 are selected, the pixel signal of the pixel G1is output to the vertical signal line VSL1, and the pixel signal of thepixel B1 is output to the vertical signal line VSL2.

Since the switches SWa11 and the SWa22 are turned off and the switchesSWa12 and SWa21 are turned on, the pixel signal of the pixel G1 outputthrough the vertical signal line VSL1 is counted by the counter 732provided corresponding to the adjacent vertical signal line VSL2, andthe pixel signal of the pixel B1 output through the vertical signal lineVSL2 is counted by the counter 731 provided corresponding to theadjacent vertical signal line VSL1.

Then, the switches SWa11 and SWa22 are turned on, and the switches SWa12and SWa21 are turned off. The pixel B2 and the pixel G3 are selected,the pixel signal of the pixel B2 is output to the vertical signal lineVSL1, and the pixel signal of the pixel G3 is output to the verticalsignal line VSL2.

Since the switches SWa11 and the SWa22 are turned on and the switchesSWa12 and SWa21 are turned off, the pixel signal of the pixel B2 outputthrough the vertical signal line VSL1 is counted by the counter 731, andthe pixel signal of the pixel G3 output through the vertical signal lineVSL2 is counted by the counter 732.

Similarly to the counting of white, since the counter 731 continues thecounting by the control of the control unit 60 until the counting of twopixels of the pixels B1 and B2, the count value of the counter 731 isdigital data corresponding to the sum of the pixel signals of the pixelsB1 and B2.

Similarly, since the counter 732 also continues the counting by thecontrol of the control unit 60 until the counting of two pixels of thepixels G1 and G3, the count value of the counter 732 is digital datacorresponding to the sum of the pixel signals of the pixels G1 and G3.

The counters 731 and 732 outputs the count values to the memories 741and 742 by the control of the timing control unit 60, respectively, whenthe counting of the pixel signals of two pixels is completed.

That is, the timing control unit 60 does not Initialize the count valuesin the counters 731 and 732 until the counting of two pixels iscompleted, and initializes the count values of the counters 731 and 732when the counting of two pixels.

As a result, the digital data formed by summing up the pixels B1 and B2and the digital data formed by summing up the pixels G1 and G3 arestored in the memories 741 and 742, respectively. The digital datastored in the memories 741 and 742 are output to the output circuit 90through the horizontal signal line during the addition process performedthereafter by the control of the timing control unit 60.

By performing the same addition operation on the pixels R1, R2, G2, andG4, the digital data formed by summing up the pixels R1 and R2 and thedigital data formed by summing up the pixels G2 and G4 are stored in thememories 741 and 742, and are output to the output circuit 90 throughthe horizontal signal line during the addition process performedthereafter by the control of the timing control unit 60.

FIG. 15A and FIG. 15B are diagrams illustrating a reading image in theaddition operation described with reference to FIG. 13 and FIG. 14. Asshown in FIG. 15A, by performing the addition operation described above,with respect to the white pixel, digital data formed by adding a whitepixel adjacent in an oblique direction is acquired, and with respect toRGB pixels, digital data formed by adding the same color of pixelsdeviate in an oblique direction by two pixels are acquired.

However, as shown in FIG. 15B, the addition value of the white pixelobtained by the addition operation of the timing chart shown in FIG. 14corresponds to the pixel value at the center of the FD sharing pixelunit, but the addition value of the RGB pixels corresponds to the pixelvalue at a position deviating from the center of the FD sharing pixelunit.

When the addition operation is performed, it is possible to adjust thefinally obtained addition value of the pixel to be close to the pixelvalue at the center of the FD sharing pixel unit by adjusting a gain inthe A/D conversion.

FIG. 16 is a timing chart illustrating an addition operation of thefirst embodiment performed while adjusting the gain. The gain adjustmentmay be realized, for example, by adjusting the slope of the referencesignal generated by the reference signal generating unit 80 as describedabove. That is, to raise the gain, it is preferable to decrease theslope of the reference signal, and to lower the gain, it is preferableto increase the slope of the reference signal.

As shown in FIG. 16, the gain is 12 dB at the time of reading the pixelsB1, G1, R2, and G4, and the gain is 0 dB at the time of reading thepixels W1 to W8 and the pixels B2, G3, R1, and G2. That is, byincreasing one gain of two pixels added in FIG. 15 more than the othergain, the position corresponding to the addition value is adjusted toapproach the pixel position of the higher gain side. The gain valuedescribed herein is an example, and it is obvious that it is arbitrarilyadjusted.

FIG. 17 is a diagram illustrating a reading image obtained as a resultof the gain adjustment shown in FIG. 16.

As shown in FIG. 17, the position corresponding to the addition value ofthe pixel B1 and the pixel B2 is close to the pixel position of thepixel B1 by increasing the gain of the pixel B1 higher than that of thepixel B2, the position corresponding to the addition value of the pixelG1 and the pixel G3 is close to the pixel position of the pixel G1 byincreasing the gain of the pixel G1 higher than that of the pixel G3,the position corresponding to the addition value of the pixel R1 and thepixel R2 is close to the pixel position of the pixel R2 by increasingthe gain of the pixel R2 higher than that of the pixel R1, and theposition corresponding to the addition value of the pixel G2 and thepixel G4 is close to the pixel position of the pixel G4 by increasingthe gain of the pixel G4 higher than that of the pixel G2.

Since the positions of the white pixels W1 to W8 corresponding to theaddition value originally correspond to the center of each pixel unit,it is not necessary to adjust the gain in the first embodiment, and thewhite pixels W1 to W8 correspond to the same position shown in FIG. 15B.

(3) Second Embodiment of Pixel Addition

Next, a second embodiment of pixel addition will be described. In thesecond embodiment, a color filter array including white is employed, andthe shift-correction type is employed in the column processing unit.

FIG. 18 is a diagram illustrating configurations of a color filter arrayand a column processing unit according to the second embodiment.Similarly to the first embodiment, in the color filter array as shown inFIG. 18, 16 pixels of 4×4 are shown, W filters with the highest outputlevel are disposed in a checkerboard shape, R and B filters are arrangedin a checkerboard shape at a pitch of two pixels vertically andhorizontally, the R and B filters are arranged to obliquely deviate atpitch of one pixel, and the remaining pixels are G filters.

In the pixel array, four pixels of the vertical and horizontal 2×2constitute the FD sharing pixel unit.

Specifically, the upper left four pixels (B1, R1, W1, and W2) constituteone FD sharing pixel unit, and the lower left four pixels (G3, G4, W5,and W6) constitute one FD sharing pixel unit. The FD sharing pixel unitsare connected to the vertical signal line VSL1 through each sharing FD.

The upper right four pixels (G1, G2, W3, and W4) constitute one FDsharing pixel unit, and the lower right four pixels (B, R, W7, and W8)constitute one FD sharing pixel unit. The FD sharing pixel units areconnected to the vertical signal line VSL2 through each sharing FD.

Two pixels (B2 and R2) shown at the lower left portion are pixelsconnected to the vertical signal line VSL0 (not shown) adjacent to theleft side of the vertical signal line VSL1, and is counted by thecounter 731 when the switch SWb01 is turned on.

The pixel signal output through the vertical signal line VSL0 (notshown) is input to a comparator 720 (not shown) provided correspondingto the vertical signal line VSL0. The comparator 720 determinesmagnitude between the reference signal input from the DAC 80 and thepixel signal. For example, when a gradually increased ramp wave is usedas the reference signal, the comparator 720 outputs Low when thereference signal is lower than the pixel signal, and outputs High whenthe reference signal is equal to or higher than the pixel signal.

The pixel signal output through the vertical signal line VSL1 is inputto the comparator 721. The comparator 721 determines magnitude betweenthe reference signal input from the DAC 80 and the pixel signal. Forexample, when a gradually increased ramp wave is used as the referencesignal, the comparator 721 outputs Low when the reference signal islower than the pixel signal, and outputs High when the reference signalis equal to or higher than the pixel signal.

The pixel signal output through the vertical signal line VSL2 is inputto the comparator 722. The comparator 722 determines magnitude betweenthe reference signal input from the DAC 80 and the pixel signal. Forexample, when a gradually increased ramp wave is used as the referencesignal, the comparator 722 outputs Low when the reference signal islower than the pixel signal, and outputs High when the reference signalis equal to or higher than the pixel signal.

The output terminal of the comparator 720 (not shown) is connected tothe counter 731 provided corresponding to the vertical signal line VSL1through SWb01.

The output terminal of the comparator 721 is connected to the counter731 provided corresponding to the vertical signal line VSL1 through theswitch SWb11, and is connected to the counter 732 provided correspondingto the vertical signal line VSL2 through the switch SWb12. The verticalsignal line VSL2 is a vertical signal line disposed adjacent to theright side of the vertical signal line VSL1.

The output terminal of the comparator 722 is connected to the counter732 provided corresponding to the vertical signal line VSL2 through theswitch SWb22, and is connected to the counter 733 provided correspondingto the vertical signal line VSL3 (not shown) through the switch SWb23.The vertical signal line VSL3 is a vertical signal line disposedadjacent to the right side of the vertical signal line VSL2.

The ON/OFF of The switches SWb01, SWb11, SWb12, SWb22, and SWb23 iscontrolled by the SW control signal output through the SW control lineby the timing control unit 60. The switches are turned on or off tosatisfy the relationship shown in FIG. 7 described above.

FIG. 19 is a timing chart according to an addition operation of thesecond embodiment.

First, an addition operation of white pixels that are the main componentof brightness will be described. To perform the addition of the whitepixels, the switches SWb11 and SWb22 are turned on, and the switchesSWb12 and SWb23 are turned off.

The pixel W1 and the pixel W3 are selected, the pixel signal of thepixel W1 is output to the vertical signal line VSL1, and the pixelsignal of the pixel W3 is output to the vertical signal line VSL2. Then,the pixel W2 and the pixel W4 are selected, the pixel signal of thepixel W2 is output to the vertical signal line VSL1, and the pixelsignal of the pixel W4 is output to the vertical signal line VSL2.

That is, the pixel signals of the pixels W1 and W2 are sequentiallyoutput to the vertical signal line VSL1, and the pixel signals of thepixels W3 and W4 are sequentially output to the vertical signal lineVSL2.

Since the switches SWb11 and SWb22 are turned on and the switches SWb12and SWb23 are turned off, both pixel signals of the pixels W1 and W2 arecounted by the counter 731, and both pixel signals of the pixels W3 andW4 are counted by the counter 732.

The counter 731 continues the counting by the control of the timingcontrol unit 60 without initializing the count until the counting ofboth pixel signals of the pixels W1 and W2 is completed. Accordingly,the count value of the counter 731 is digital data corresponding to thesumming of the pixel signals of the pixels W1 and W2.

Similarly, the counter 732 continues the counting by the control of thetiming control unit 60 without initializing the count until the countingof both pixel signals of the pixels W3 and W4 is completed. Accordingly,the count value of the counter 732 is digital data corresponding to thesumming of the pixel signals of the pixels W3 and W4.

In other words, the timing control unit 60 does not initialize the countvalues by the counters 731 and 732 until the counting of two pixels asthe addition target, and initializes the count values of the counters731 and 732 when the counting of two pixels as the addition target iscompleted and the count values are output to the memories 741 and 742(see FIG. 2).

When the counting of the pixel signals of two pixels is completed, thecounters 731 and 732 outputs the count values to the memories 741 and742 by the control of the timing control unit 60.

As a result, the digital data formed by summing up the pixels W1 and W2and the digital data formed by summing up the pixels W3 and W4 arestored in the memories 741 and 742, respectively. The digital datastored in the memories 741 and 742 are output to the output circuit 90through the horizontal signal lines, during the addition processperformed thereafter by the control of the timing control unit 60.

By performing the same addition operation on the pixels W5, W6, W7, andW8 that are the other white pixels, the digital data formed by summingup the pixels W5 and W6 and the digital data formed by summing up thepixels W7 and W8 are stored in the memories 741 and 742, and the digitaldata are output to the output circuit 90 through the horizontal signallines during the addition process performed thereafter by the control ofthe timing control unit 60.

Next, the addition operation of the R, G, and B pixels will bedescribed. In the second embodiment, the addition operation of the whitepixels is first performed, and the addition operation of the RGB pixelsis performed thereafter. However, of course, the sequence may be reverseand alternate, and the sequence may be appropriately changed.

To add the R, G, and B pixels, first, the switches SWb11 and the SWb22are turned on and the switches Swb12 and Swab23 (and the switch SWb01)are turned off. The pixel B1 and the pixel G1 are selected, the pixelsignal of the pixel B1 is output to the vertical signal line VSL1, andthe pixel signal of the pixel G1 is output to the vertical signal lineVSL2.

Since the switches SWb11 and the SWb22 are turned on and the switchesSWb12 and SWb23 are turned off, the pixel signal of the pixel B1 outputthrough the vertical signal line VSL1 is counted by the counter 731provided corresponding to the vertical signal line VSL1, and the pixelsignal of the pixel G1 output through the vertical signal line VSL2 iscounted by the counter 732 provided corresponding to the vertical signalline VSL2.

Then, the switches SWb11 and SWb22 are turned off, and the switchesSWb12 and SWb23 (and the switch SWb01) are turned on. The pixel B2 andthe pixel G3 are selected, the pixel signal of the pixel B2 is output tothe vertical signal line VSL0 (not shown), and the pixel signal of thepixel G3 is output to the vertical signal line VSL1.

Since the switches SWb11 and the SWb22 are turned off and the switchesSWb12 and SWb23 (and the switch SWb01) are turned on, the pixel signalof the pixel B2 output through the vertical signal line VSL0 (not shown)is counted by the counter 731, and the pixel signal of the pixel G3output through the vertical signal line VSL1 is counted by the counter732.

Similarly to the counting of white, since the counter 731 continues thecounting by the control of the control unit 60 until the counting of twopixels of the pixels B1 and B2, the count value of the counter 731 isdigital data corresponding to the sum of the pixel signals of the pixelsB1 and B2.

Similarly, since the counter 732 also continues the counting by thecontrol of the control unit 60 until the counting of two pixels of thepixels G1 and G3, the count value of the counter 732 is digital datacorresponding to the sum of the pixel signals of the pixels G1 and G3.

The counters 731 and 732 outputs the count values to the memories 741and 742 by the control of the timing control unit 60, respectively, whenthe counting of the pixel signals of two pixels is completed.

That is, the timing control unit 60 does not initialize the count valuesin the counters 731 and 732 until the counting of two pixels iscompleted, and initializes the count values of the counters 731 and 732when the counting of two pixels.

As a result, the digital data formed by summing up the pixels B1 and B2and the digital data formed by summing up the pixels G1 and G3 arestored in the memories 741 and 742, respectively. The digital datastored in the memories 741 and 742 are output to the output circuit 90through the horizontal signal line during the addition process performedthereafter by the control of the timing control unit 60.

By performing the same addition operation on the pixels R1, R2, G2, andG4, the digital data formed by summing up the pixels R1 and R2 and thedigital data formed by summing up the pixels G2 and G4 are stored in thememories 741 and 742, and are output to the output circuit 90 throughthe horizontal signal line during the addition process performedthereafter by the control of the timing control unit 60.

FIG. 20A and FIG. 20B are diagrams illustrating a reading image in theaddition operation described with reference to FIG. 18 and FIG. 19. Asshown in FIG. 20A, by performing the addition operation described above,with respect to the white pixel, digital data formed by adding a whitepixel adjacent in an oblique direction is acquired, and with respect toRGB pixels, digital data formed by adding the same color of pixelsdeviate in an oblique direction by two pixels are acquired.

However, as shown in FIG. 20B, the addition value of the white pixelobtained by the addition operation of the timing chart shown in FIG. 19corresponds to the pixel value at the center of the FD sharing pixelunit, but the addition value of the RGB pixels corresponds to the pixelvalue at a position deviating from the center of the FD sharing pixelunit.

When the addition operation is performed, it is possible to adjust thefinally obtained addition value of the pixel to be close to the pixelvalue at the center of the FD sharing pixel unit by adjusting a gain inthe A/D conversion.

FIG. 21 is a timing chart illustrating an addition operation of thesecond embodiment performed while adjusting the gain.

As shown in FIG. 21, the gain is 6 dB at the time of reading the pixelsB1, G1, R1, and G2, and he gain is 0 dB at the time of reading thepixels W1 to W8 and the pixels B2, G3, R2, and G4. That is, byincreasing one gain of two pixels added in FIG. 20 more than the othergain, the position corresponding to the addition value is adjusted toapproach the pixel position of the higher gain side.

More specifically, to adjust the addition value of the pixel tocorrespond to the center of the FD sharing pixel unit, the gain of thepixels B1, G1, R1, and G2 is 6.64 dB when the gain of the pixels B2, G3,R2, and G4 is 0 dB such that a ratio of the gain of the pixels B1, G1,R1, and G2 and the gain of the pixels B2, G3, R2, and G4 is 3:1.

FIG. 22 is a diagram illustrating a reading image obtained as a resultof the gain adjustment shown in FIG. 21.

As shown in FIG. 22, the position corresponding to the addition value ofthe pixel B1 and the pixel B2 is close to the pixel position of thepixel B1 by increasing the gain of the pixel B1 higher than that of thepixel B2, the position corresponding to the addition value of the pixelG1 and the pixel G3 is close to the pixel position of the pixel G1 byincreasing the gain of the pixel G1 higher than that of the pixel G3,the position corresponding to the addition value of the pixel R1 and thepixel R2 is close to the pixel position of the pixel R2 by increasingthe gain of the pixel R2 higher than that of the pixel R1, and theposition corresponding to the addition value of the pixel G2 and thepixel G4 is close to the pixel position of the pixel G4 by increasingthe gain of the pixel G4 higher than that of the pixel G2,

Since the positions of the white pixels W1 to W8 corresponding to theaddition value originally correspond to the center of each pixel unit,the gain is not performed in the second embodiment, and the white pixelsW1 to W8 correspond to the same position shown in FIG. 20B.

(4) Third Embodiment of Pixel Addition

Next, a third embodiment of pixel addition will be described. In thethird embodiment, a color filter array of Bayer arrangement in therelated art, and the cross-Connection type described is employed in thecolumn processing unit.

FIG. 23 is a diagram illustrating configurations of a color filter arrayand a column processing unit according to the third embodiment. Thecolor filter array shown in FIG. 13 shows 16 pixels of 4×4 similarly tothe first embodiment. In the pixel array, four pixels of the verticaland horizontal 2×2 constitute the FD sharing pixel unit.

Specifically, the upper left four pixels (R1, B1, G, and G) constituteone FD sharing pixel unit, and the lower left four pixels (G2, G4, R,and B) constitute one FD sharing pixel unit. The FD sharing pixel unitsare connected to the vertical signal line VSL1 through each sharing FD.

The upper right four pixels (R, B, G1, and G3) constitute one FD sharingpixel unit, and the lower right four pixels (R2, B2, G, and G)constitute one FD sharing pixel unit. The FD sharing pixel units areconnected to the vertical signal line VSL2 through each sharing FD.

The pixel signal output through the vertical signal line VSL1 is inputto the comparator 721. The comparator 721 determines magnitude betweenthe reference signal input from the DAC 80 and the pixel signal. Forexample, when a gradually increased ramp wave is used as the referencesignal, the comparator 721 outputs Low when the reference signal islower than the pixel signal, and outputs High when the reference signalis equal to or higher than the pixel signal.

Meanwhile, the pixel signal output through the vertical signal line VSL2is input to the comparator 722. The comparator 722 determines magnitudebetween the reference signal input from the DAC 80 and the pixel signal.For example, when a gradually increased ramp wave is used as thereference signal, the comparator 722 outputs Low when the referencesignal is lower than the pixel signal, and outputs High when thereference signal is equal to or higher than the pixel signal.

The output terminal of the comparator 721 is connected to the counter731 provided corresponding to the vertical signal line VSL1 through theswitch SWa11, and is connected to the counter 732 provided correspondingto the vertical signal line VSL2 through the switch SWa12. The verticalsignal line VSL2 is a vertical signal line disposed adjacent to thevertical signal line VSL1.

The output terminal of the comparator 722 is connected to the counter732 provided corresponding to the vertical signal line VSL2 through theswitch SWa22, and is connected to the counter 731 provided correspondingto the vertical signal line VSL1 through the switch SWa21. The verticalsignal line VSL1 is a vertical signal line disposed adjacent to thevertical signal line VSL2.

The ON/OFF of The switches SWa11, SWa12, SWa22, and SWa21 is controlledby the SW control signal output through the SW control line by thetiming control unit 60. The switches are turned on or off to satisfy therelationship shown in FIG. 3 described above.

FIG. 24 is a timing chart according to an addition operation of thethird embodiment.

First, the switches SWa11 and SWa22 are turned on, and the switchesSWa12 and SWa21 are turned off. The pixel R1 is selected, and the pixelsignal of the pixel R1 is output to the vertical signal line VSL1.Herein, since the switches SWa11 and SWa22 are turned on and theswitches SWa12 and SWa21 are turned off, the pixel signal of the pixelR1 is counted by the counter 731.

Then, the switches SWa11 and SWa22 are turned off, and the switchesSWa12 and SWa21 are turned on. The pixel R2 is selected, and the pixelsignal of the pixel R2 is output to the vertical signal line VSL2.Herein, since the switches SWa11 and SWa22 are turned off and theswitches SWa12 and SWa21 are turned on, the pixel signal of the pixel R2is counted by the counter 731.

The counter 731 continues the counting by the control of the timingcontrol unit 60 without initializing the count until the counting ofboth pixel signals of the pixels R1 and R2 is completed. Accordingly,the count value of the counter 731 is digital data corresponding to thesumming of the pixel signals of the pixels R1 and R2.

Then, the switch stands as it is, the pixel G1 is selected, and thepixel signal of the pixel G1 is output to the vertical signal line VSL2.Then, the pixel signal of the pixel G1 is counted by the counter 731.

Then, the switches SWa11 and SWa22 are turned on, and the switches SWa12and SWa21 are turned off. The pixel G2 is selected, and the pixel signalof the pixel G2 is output to the vertical signal line VSL1. Then, thepixel signal of the pixel G2 is counted by the counter 731.

As described above, the ON/OFF of the switches and the outputs of thecount values are alternately repeated, and thus it is possible tosequentially output the addition values of the pixels to the outputcircuit 90 with respect to the remaining pixels G4, G3, B2, and B1.

In the third embodiment, the comparator 722, the counter 732, and thememory 742 provided corresponding to the signal line VSL2 are not used,and thus it is possible to reduce power consumption with such aconfiguration as a standby state.

FIG. 25A and FIG. 25B are diagrams illustrating a reading image in theaddition operation described with reference to FIG. 23 and FIG. 24. Asshown in FIG. 25A, by performing the addition operation described above,with respect to the white pixel, with respect to RGB pixels, digitaldata formed by adding the same color of pixels deviate in an obliquedirection by two pixels are acquired.

However, as shown in FIG. 25B, the addition values of the RGB pixelsobtained by the addition operation of the timing chart shown in FIG. 24corresponds to the pixel value at a position deviating from the centerof the FD sharing pixel unit.

When the addition operation is performed, it is possible to adjust thefinally obtained addition value of the pixel to be close to the pixelvalue at the center of the FD sharing pixel unit by adjusting a gain inthe A/D conversion.

FIG. 26 is a timing chart illustrating an addition operation of thethird embodiment performed while adjusting the gain.

As shown in FIG. 26, the gain is 6 dB at the time of reading the pixelsR1, G1, G4, and B2, and he gain is 0 dB at the time of reading thepixels R2, G2, G3, and B1. That is, by increasing one gain of two pixelsadded in FIG. 25 more than the other gain, the position corresponding tothe addition value is adjusted to approach the pixel position of thehigher gain side.

FIG. 27 is a diagram illustrating a reading image obtained as a resultof the gain adjustment shown in FIG. 26.

As shown in FIG. 27, the position corresponding to the addition value ofthe pixel R1 and the pixel R2 is close to the pixel position of thepixel R1 by increasing the gain of the pixel R1 higher than that of thepixel R2, the position corresponding to the addition value of the pixelG1 and the pixel G2 is close to the pixel position of the pixel G1 byincreasing the gain of the pixel G1 higher than that of the pixel G2,the position corresponding to the addition value of the pixel G4 and thepixel G3 is close to the pixel position of the pixel G4 by increasingthe gain of the pixel G4 higher than that of the pixel G3, and theposition corresponding to the addition value of the pixel B2 and thepixel B1 is close to the pixel position of the pixel B2 by increasingthe gain of the pixel B2 higher than that of the pixel B1.

(5) Various Modification Examples

(5-1) First Modification Example

In the embodiments, the FD addition method may be used together.

That is, a plurality of pixels are selected from the FD sharing pixelunit, charges are output from photodiodes of the plurality of pixels tothe floating diffusion, and the pixel value is analog-added in advanceto the floating diffusion FD and is output to the vertical signal line.

For example, in the first embodiment and the second embodiment, when twowhite pixels belonging to one FD sharing pixel unit are subjected to FDaddition and are output, it is possible to reduce a process time takingin the outputting of the white pixels by half.

(5-2) Second Modification Example

In the embodiments and modification examples described above, the caseof performing the decimation outputting of 16 pixels of vertical andhorizontal 4×4 into four pixels of vertical and horizontal 2×2 has beendescribed, but it is obvious that the disclosure may correspond variousdecimation degrees, for example, the decimation outputting of 64 pixelsof vertical and horizontal 8×8 into four pixels of vertical andhorizontal 2×2.

(5-3) Third Modification Example

In the embodiments and modification examples described above, thecomparator and counter corresponding to each vertical signal line areconnected to the first switch, and the comparator corresponding to eachvertical signal line and the counter corresponding to the adjacentvertical signal are connected to the second switch. However, thedisclosure is not limited to the case where the counter that is theconnection destination of the second switch does not necessarilycorrespond to the vertical signal line.

FIG. 28 is a diagram illustrating a connection relationship according tothe third modification example. A basic configuration of FIG. 28 is thesame as that of FIG. 2, and the connection relationship of the switchcircuit SWa is changed and shown.

The switch circuit SWa includes switches SWa11, SWa1 m, SWam1, andSWamm. The comparator 721 and the counter 731 are connected through theswitch SWa11, and the comparator 72 m and the counter 73 m are connectedthrough the switch SWamm. The comparator 721 and the counter 73 m areconnected through the switch SWa1 m, and the comparator 72 m and thecounter 731 are connected through the switch SWam1.

That is, the switch circuit SWa includes a switch connecting acomparator and a counter provided corresponding one vertical signalline, and a switch connecting a comparator provided corresponding to onevertical signal line and a counter provided corresponding to the othervertical signal line different from the one vertical signal line.

For this reason, in one set of vertical signal lines VSL1 and VSLm, anyone of the counter provided corresponding to one vertical signal line,and the counter provided corresponding to the other vertical signal lineis selected to perform the counting. The set of vertical signal linesVSL1 and VSLm may be adjacent or may not be adjacent.

Accordingly, the pixel values of the pixel connected to the verticalsignal line VSL1 and the pixel connected to the vertical signal lineVSLm can be added and output by the counter 731 and the counter 73 m.

Herein, the cross-connection type column processing unit 70 has beendescribed as an example, but it is obvious that the third modificationexample can be applied to the shift-connection type column processingunit 70.

(5-4) Fourth Modification Example

In the embodiments and modification examples described above, onevertical signal line is provided in two pixel columns, but of course,one vertical signal line may be provided in one pixel column, and onevertical signal line may be provided in three or more pixel columns,

The present technology is not limited to the embodiment and modificationexamples described above, and includes a configuration in which theconfigurations disclosed in the embodiment and modification examplesdescribed above are substituted or the combinations thereof aremodified, and a configuration in which the configurations disclosed inthe related art and the embodiment and modification examples describedabove are substituted or the combinations thereof are modified. Thetechnical scope of the present technology is not limited to theembodiments described above, and includes the items described in Claimsand equivalents thereof.

The present technology may have the following configuration.

(1) A solid state imaging device including: a pixel array unit that hasa plurality of pixels 2-dimensionally arranged in a matrix and aplurality of signal lines arranged along a column direction; A/Dconversion units that are provided corresponding to the respectivesignal lines and convert an analog signal output from a pixel throughthe signal line into a digital signal; and a switching unit thatswitches or converts the analog signal output through each signal lineinto a digital signal using any of an A/D conversion unit providedcorresponding to the signal line through which the analog signal istransmitted, and an A/D conversion unit provided corresponding to asignal line other than the signal line through which the analog signalis transmitted.

(2) The solid state imaging device according to (1), wherein the A/Dconversion unit has a comparator that compares a time-variable referencesignal with an analog signal obtained from the pixel, and a counter thatcounts a time until the comparison is completed in the comparator, andwherein the switching unit includes a first switch that connects anoutput terminal of the comparator in the A/D conversion unit providedcorresponding to each signal line to an input terminal of the counter, asecond switch that connects an output terminal of the comparator in theA/D conversion unit provided corresponding to each signal line to aninput terminal of the counter of the A/D conversion unit providedcorresponding to the other signal line, and a switching control unitthat controls switching of the first switch and the second switch.

(3) The solid state imaging device according to (1) or (2), wherein theswitching unit switches or converts the analog signal output from one oftwo signal lines into a digital signal using any of the A/D conversionunit provided corresponding to one signal line and the A/D conversionunit provided corresponding to the other signal line.

(4) The solid state imaging device according to any one of (1) to (3),wherein the switching unit switches or converts the analog signal outputthrough each signal line of the plurality of signal lines into a digitalsignal using any of the A/D conversion unit provided corresponding tothe signal line through which the analog signal is transmitted, and theA/D conversion unit provided corresponding to the signal line providedto be adjacent to one side of the signal line through which the analogsignal is transmitted.

(5) The solid state imaging device according to any one of (1) to (4),wherein a predetermined number of pixels of the plurality of pixelsshare a floating diffusion, and wherein the switching unit performsanalog addition of analog signals of two or more pixels sharing the samefloating diffusion by the floating diffusion and outputs theanalog-added signals to the signal lines.

(6) The solid state imaging device according to any one of (1) to (5),wherein the plurality of pixels is provided with a color filter array inwhich colors of filters are classified corresponding to the respectivepixels, on a light reception face side, and wherein white filters of thecolor filter array are disposed in a checkerboard shape, red and bluefilters are arranged in a checkerboard shape at a pitch of two pixelsvertically and horizontally, the red and blue filters are arranged toobliquely deviate by one pixel, and the remaining pixels are greenfilters.

(7) The solid state imaging device according to any one of (1) to (6),wherein the plurality of pixels are provided with a color filter arrayin which colors of filters are classified corresponding to therespective pixels, on the light reception face side, and wherein in thecolor filter array, the color filters are arranged in a Bayerarrangement.

(8) A method of controlling a solid state imaging device including apixel array unit that has a plurality of pixels 2-dimensionally arrangedin a matrix and a plurality of signal lines arranged along a columndirection, and A/D conversion units that are provided corresponding tothe signal lines and convert an analog signal output from a pixelthrough the signal line into a digital signal, the method including:switching conversion of the analog signal output through each signalline into a digital signal using any of an A/D conversion unit providedcorresponding to the signal line through which the analog signal istransmitted, and an A/D conversion unit provided corresponding to asignal line other than the signal line through which the analog signalis transmitted.

(9) A program for controlling a solid state imaging device including apixel array unit that has a plurality of pixels 2-dimensionally arrangedin a matrix and a plurality of signal lines arranged along a columndirection, and A/D conversion units that are provided corresponding tothe signal lines and convert an analog signal output from a pixelthrough the signal line into a digital signal, the program including: aswitching function of switching conversion of the analog signal outputthrough each signal line into a digital signal using any of an A/Dconversion unit provided corresponding to the signal line through whichthe analog signal is transmitted, and an A/D conversion unit providedcorresponding to a signal line other than the signal line through whichthe analog signal is transmitted.

The present disclosure contains subject matter related to that disclosedin Japanese Priority Patent Application JP 2011-207368 filed in theJapan Patent Office on Sep. 22, 2011, the entire contents of which arehereby incorporated by reference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. An imaging device comprising: a plurality ofpixels including a first pixel configured to output a first pixelsignal, a second pixel configured to output a second pixel signal, and athird pixel configured to output a third pixel signal; a first signalline coupled to the first signal pixel; a second signal line coupled tothe second signal pixel; a third signal line coupled to the third pixel;a first comparator coupled to the first signal line and configured tooutput a first determination signal based on the first pixel signal; athird comparator coupled to the third signal line and configured tooutput a third determination signal based on the third pixel signal; asecond comparator coupled to the second signal line and configured tooutput a second determination signal based on the second pixel signal,wherein the second comparator is arranged between the first comparatorand the third comparator; a first counter, a second counter and a thirdcounter, wherein the second counter is arranged between the firstcounter and the third counter; a first switch circuit configured tocouple the first comparator to the first counter; and a second switchcircuit configured to couple the first comparator to the third counter;wherein the first counter is configured to receive the firstdetermination signal when the first switch circuit couples the firstcomparator to the first counter, and wherein the third counter isconfigured to receive the first determination signal when the secondswitch circuit couples the first comparator to the third counter.
 2. Theimaging device according to claim 1, further comprising: a third switchcircuit configured to couple the third comparator to the first counter;wherein the first counter is configured to receive the thirddetermination signal when the third switch circuit couples the thirdcomparator to the first counter.